Chinese Patent CN101388477B discloses a rapid charging method which increases the limited charge voltage to compensate the internal voltage drop of the battery. During the charging of lithium-ion battery and polymer lithium-ion battery, stop charging the battery when it is charged to the limited charge voltage; the limited charge voltage between the two poles of the battery is set as U=2U0−US, wherein US is the stabilized voltage dropped from U0 which the battery is charged to by constant-current charging; wherein U0 is charge cut-off voltage and commonly recognized by the industry as the charge cut-off voltage used by the low power constant-current and constant-voltage charging method; The stabilized voltage US is selected by conducting timing when stopping constant-current charging the battery and starting to lay up the battery; from some time point, when the open-circuit voltage drop of the battery over a certain time period is smaller than a certain value, the battery voltage would reach a steady state; the voltage at the first time point is selected as the stabilized voltage US of the battery.
When the method is applied in lithium iron phosphate battery, U0 is charge cut-off voltage of 3.6V which is commonly recognized by the industry as the charge cut-off voltage used in the low power constant-current and constant-voltage charging method; the battery is charged to U=2U0−US, which is not charged to saturation, but only reaches 88% of the saturation point, thus failing to make the most of the battery. Also 3.5V, 3.65V and 3.7V are commonly recognized by the industry as the charge cut-off voltage used by the low power constant-current and constant-voltage charging method, however the battery is charged to U=2U0−US which is not charged to saturation, therefore, they all could not make the most of the battery efficiency.
When the method is applied in Lithium cobalt battery, U0 is charge cut-off voltage of 4.2V which is commonly recognized by the industry as the charge cut-off voltage used by the low power constant-current and constant-voltage charging method; the battery is charged to U=2U0−US and is not charged to saturation, but only reaches 97% of the saturation point, which could not make the most of the battery.
In order to make the most of the battery efficiency, it is necessary to make appropriate corrections to the limited charge voltage.